Fridge Defend by ARP Keeps Your Valuables Safe

WITHOUT FRIDGE DEFEND YOU ARE NOT PROTECTED

Dometic & Norcold reliability and fire safety, can you live without it?

Norcold AC Heater | Norcold Heating Element | Norcold Heater Resistance

If you want to know how to troubleshoot and fix Norcold shower power (AC) heaters, this page teaches how to test and repair these heaters.

Table of Contents

Instructions: Subjects are listed on left. Click the link to the right to go directly to the subject matter on this page.

We included this video on the page to show how to test the Norcold electric heaters. This video covers electrical safety, Norcold controller fuses, troubleshooting AC heater, Ohms test for heaters, & heater short test.

For those that like written instruction with details – please read on:
Norcold Fail
ELECTRIC HEATERS – NO COOLING ON SHORE POWER This photo is looking into a typical Norcold refrigerator access panel. The blue arrow points to the shore power (AC) heater wire. The wire runs from the controller on the left to the boiler housing on the right.

This Norcold fridge has 2 AC heaters, one failed. This fridge had poor cooling on shore power, in addition this fridge was equipped with the Fridge Defend. The Fridge Defend keep tripping due to the overheat situation that was caused by one of the two heaters failing.

The Norcold recalls will not respond to this situation and the fridge will be damaged unless this no cooling on shore power problem is fixed, click here to learn more about why the recalls cannot protect your fridge!

TYPICAL RV FRIDGE AC HEATER SPECIFICATIONS

The following values are for a Norcold 1210 series; you can get the specifications for any Norcold fridge by clicking here and use your model number.
Fuse: 5A (AGC type fast acting)
Power: 225W per heater
Resistance @ 72°F: 64 Ohms per heater
Troubleshoot Norcold Electric Heaters

HOW TO TEST NORCOLD HEATERS

This drawing shows how to test Norcold heaters, this example is for Norcold models 1200, 1210, or 2118, but the principles are the same for any model. The first step is to remove the heater wires from the Norcold control board. The cover for the Norcold controller generally needs to be removed, test the fuse, if the fuse needs to be replaced, be sure to replace with the exact fuse that belongs on your controller.

Click here and use your Norcold model number to find the proper fuse & resistance (ohms) for your AC heaters .

Once the heater wire is removed from the controller, an ohm meter or DMM can be used to test the heater. The resistance for the heater can be found by clicking the link directly above.

Generally the ohms specification (resistance) is for a cool heater, thus if you have a Fridge Defend check the boiler temperature. The upper DMM in this drawing shows the meter measuring the heater resistance, the lower DMM shows reading the continuity between the heater and ground. If the heater shows resistance between the wire and the heater housing (ground), the heater has failed.
One Heater Failed RV Fridge

Norcold 1200, 2010 & 2118 Series
What if One Heater Fails?

The curve to the left is of a Norcold 1210 refrigerator boiler using the ARP Data Collection control. This outcome is the same for any Norcold fridge with a heater problem where the quality of heat is an issue. Following is a description of the events captured in this session:

A) The refrigerator goes through a normal cooling period with both heaters connected and working properly. The refrigerator thermostat turns on the cooling unit; the temperature rises, and then holds at about 187°C. The refrigerator cabinet temperature is 38°F.

B) One heater is disconnected, then the refrigerator is allowed to go through 3 more cycles.

C) Note that the maximum temperature is now 192°C on startup.

D) One heater is disconnected, and then the refrigerator is allowed to go through 3 more cycles. The cabinet temperature rose from 38°F to 45°F.

CONSEQUENCES: If the fridge is allowed to keep running, the boiler eventually overheats. One may ask:

  • Why does the boilers curve changes with just one heater operating?

  • Why would the boiler overheat when there is not enough heat?

    • The answers are simple, "quality of heat". We will move on to the answers after talking about safety:

    SAFETY: This fridge had the Fridge Defend; it was brought to us because they thought they had a problem with the Fridge Defend. It turns out that the Fridge Defend was just doing its job, detecting an unsafe condition that the Norcold recall cannot detect.

    ANSWER : The manufactures state that “the proper amount of heat needs to be applied to the boiler”. In scientific terms, this is called quality of heat. Not enough heat results in the boiler overheating due to the fact that the boiler pump cannot work properly, this reduces the refrigerant flow, and in turn the boiler overheats. This ultimately destroys the fridge which can result in fire danger.

    How to Calculate any Fridge Heater Resistance

    The resistance for any heating element can be calculated if you know the power in Watts (W). This information can usually be found on the refrigerator tag on the fridge door cell. Open the door or the fridge and look for the tag that gives model and specifications like AC Wattage. The following formula will give you resistance in two steps:

    We know that you will either be calculating a 12VDC or 120VAC heating element, thus we know the voltage (V).

    Power = Voltage times Current → P = VI → I = P/V → for the Norcold 1200 heater: I = 225W/120VAC = 1.87A

    Power = the square of current times resistance → P = (I^2)R → R = P/(I^2) → for the Norcold 1200 heater: R = 225W/(1.87)^2 = 64 Ohms

    Note that this is the same value as stated above in TYPICAL RV FRIDGE AC HEATER SPECIFICATIONS section.

    Questions?

    Please use Contact Us menu above if your Norcold cooling unit is not listed, or you have questions regarding Norcold heaters &/or the Fridge Defend Control.